The invention relates generally to components for crash test dummies and more specifically to an improved rib assembly for securement to a spine of a crash test dummy which may be used in multiples.
Beyond calculations and projections from known data, safety design for automobiles has long relied and will likely continue to rely upon the results of actual crash tests. Notwithstanding the increasing application of super computers to this task, real world, controlled and highly instrumented crashes to test both prototype and production vehicles will continue. The complement to such testing is the crash test dummy, a mannequin or simulated human form, which attempts to approximate, as closely as possible, the skeletal, muscular and organic construction of the human body. It is entirely reasonable to state that the sophistication of crash test dummies has increased commensurately with the increased emphasis on safe motor vehicles and the sophistication of data recovery from crash tests.
Perhaps the most single common raw data recorded from a crash is the displacement of vehicle structure and components as well as the displacement of crash test dummy components relative to one another. While the data recorded is typically displacement, it is recorded over time and such displacement over time is readily conditioned or recomputed to provide both speed and acceleration of such components.
Such displacement typically is measured along a single linear path or two orthogonal paths. Given the often oblique or random direction of forces relative to an axis of a linear sensor, it is apparent that forces may frequently be generated which tend to interfere with the smooth, linear operation of a component and its sensor. Such oblique or transverse forces can frequently result in binding of a component and its sensor which manifests itself in reduced linear travel and thus reduced measured displacement and computed speed and acceleration. This is a particular problem in the larger structures of a crash dummy such as the rib cage where opposed left and right ribs are separated by several inches and oblique or transverse forces may cause binding of the simulation mechanism and significantly impair accurate measurement of displacement and associated variables.
Accordingly, rib assemblies that exhibit improved resistance to binding caused by oblique or transverse forces would be highly desirable. The present invention is directed to such a device.
An improved rib assembly for a crash test dummy includes a U-shaped outer member which simulates a pair of ribs secured to a spine and a pair of transverse assemblies disposed in parallel and coupled between such opposed ribs. A first assembly is a spring centered damper which provides simulated resistance to displacement of one rib relative to another. A second assembly includes a spring biased piston and cylinder that provides simulated positioning of the rib ends. A sensor disposed generally between the two assemblies measures the displacement of one of the pair of ribs relative to the other. The piston rod is supported upon a pair of linear ball bearing assemblies which maintains alignment between these two assemblies and ensures accurate responsive motion therebetween without binding and thus accurate measurements of displacement. A plurality of U-shaped rib assemblies, typically three, may be utilized to simulate a rib cage in a crash test dummy.
Thus it is an object of the present invention to provide rib components for a crash test dummy which exhibit improved performance when subjected to oblique and transverse forces.
It is a further object of the present invention to provide rib assemblies for crash test dummies having linear ball bearing assemblies which support transversely telescoping members.
It is a still further object of the present invention to provide a rib assembly for crash test dummies which may be used in multiples in a crash test dummy.
It is a still further object of the present invention to provide a rib assembly for a crash test dummy which provides improved displacement measurements during crash tests.
Further objects and advantages of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature.